What is a Hellbender?

North American giant salamander. 
Eastern hellbenders are the largest salamander in North America. Adults are capable of reaching 29 inches in length; however, most individuals are typically 11-24 inches long. This North American giant salamander has short limbs and widely flattened head and body. A fleshy fold of skin extends along the sides of the body between the front and hind limbs giving them an overall wrinkly appearance (Figure 1). Body color is often variable, ranging from a greenish to yellowish brown. Dark spotting is typically present along the back and tail.   Although adults are quite large, they are rarely seen.  They spend most of their time hiding beneath large, flat rocks during the day and forage for crayfish at night.
Larval hellbender.
Larval hellbenders differ from adults in several ways: they possess external gills, visible yolk sacs, and lack functioning limbs at hatching.  Newly hatched larvae are extremely small, generally less than an inch in length.  They are typically uniform in color with a dark back and light belly (Figure 2).  Larvae will rely on their yolk sacs for nutrition for the first several months of life, before slowly switching to small aquatic invertebrates. The young remain in the larval stage for approximately two years before undergoing a partial transformation.  
 Two year old hellbender.
This transformation changes their physical appearance as well as their behavior. ​Dorsal spotting begins to form at 6 months (~2 – 2.5 inches) and becomes more prominent at one to two years of age (~4 – 5 inches) when external gills are lost (Figure 3).  The small, transformed juveniles will spend the next few years hiding under small stones in gravel beds.  They will require another three to four years to reach sexual maturity.
  Hellbenders are long-lived for amphibians, typically living for more than 30 years.